Comment by Pfhreak | Hacker News Reader

Comment by Pfhreak | Hacker News Reader

Interesting. Author describes a few methods for cutting fabric on a hypothetical fabric CNC. Lasers are out because of the impact to the material, so they investigate a few cutting options:

Blade - Cuts well, but drags material

Roller - Cuts well, but needs heavy downforce and overcuts the fabric border

Scissors - A mechanical nightmare

The author suggests a reciprocating blade might solve the issue, but introduces other complexities (it destroys the material underneath.

A reciprocating blade seems like a much more complex solution than trying to solve a fabric rigidity issue or heaviness issue from a rolling blade. Like, if you are already considering a sacrificial material, why not sandwich the fabric between two rigid, high friction materials, and have the knife cut through all three?

I think about this a lot, as the partner does a lot of sewing, and a significant amount of time is spent on cutting pattern pieces. It seems like such a solvable problem, but also, such a challenging problem.

If my memory can be trusted, then it can be done with a high-pressure water jet. As a kid, my class took a field trip to a factory that did this. I remember being fascinated by the idea that water could cut.

EDIT: No need to trust my memory:

https://wardjet.com/waterjets/water-only

https://textilelearner.blogspot.com/2015/07/fabric-cutting-b...

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Incidentally, this was a long time ago (~1980?), and another thing we saw was a computer whose operator explained that to boot it up, they had to go through a sequence involving toggle switches on the front panel. Someone commented that it sounds impossible, and the operator said it gets easy after a while.

They also had some stations for design work with basically a drafting table and a mouse-like device with a ~12 key keypad on it and I think a glass with a reticle, presumably for aligning with points on a blueprint or something like that.

We had a waterjet at the granite shop we worked at for cutting stone slabs. Even after years of working there, I'd still just sit and stare at it sometimes fascinated.

That thing was always a hassle with maintenance though and sometimes things on the intensifier would explode....

Programming it was pretty cool. Different than the routers I programmed. We had a camera system rigged up that could take photos of the slab. The cad files were then loaded in and dropped and arranged on the stone.

The guy that did it at our shop was really good at matching everything. Connecting the veins for pieces that needed to be joined or mitered.

A friend operates one at a granite shop. They use a software that maps the surface and then uploads it to a webapp that lets the customer choose the pattern layout.

One thing I found interesting about water jets is that you absolutely do not want to be cut by one. The force is strong enough that it can inject the abrasive garnet into your bloodstream. The machine I actually came with instructional tags to pin to the shirt of anyone headed to the ER.

>A friend operates one at a granite shop. They use a software that maps the surface and then uploads it to a webapp that lets the customer choose the pattern layout.

That would have been pretty cool. One of the biggest holdups to our schedule used to be waiting for customers to confirm layouts before cutting. They always come into the shop to verify.

We used old unsupported software called stonecam from Park Industries. Only one guy still working there had any experience with the software. We ended up having to recalibrate the camera on the machine while I was there. It involved manually configuring variables in text files with variable names written in a mix of German and English. Apparently the software was written by one German guy who vanished some time ago who never told anyone else how it all worked completely.

They'd switched to officially supporting AlphaCam a while ago. We had licenses for our two routers for alpha cam but they were ten grand a piece and the boss was holding out as long as possible before switching the waterjet over.

>The force is strong enough that it can inject the abrasive garnet into your bloodstream

Oh wow had no idea about that. I figured you absolutely did not want to get your body into the flow, but never heard that.

A person who worked on early PDPs for UNIX said he had memorized the toggle switches positions to enter the bootloader.

"Toggle these programs in at location 10000", literally there would be toggles to enter the machine location 10000 and the series of instructions that would be pasted into it.

>I remember being fascinated by the idea that water could cut.

It doesn't. Water is a really poor cutting agent. The water is just used to propel abrasive garnet at high pressures. If there was a cheaper and better way to move the garnet then someone would have already done so without water.

Not entirely accurate. Certainly for metals, stone, and other hard materials the entrained abrasive is doing the cutting, but water-only waterjet cutting is used for a lot of things: foams, rubbers, plastics, fibrous materials, food, sensitive items like diapers and medical materials (because the pressurized water is inherently sterilized, and there's no blade to gum up and hold bacteria).

And what's really going to bake your noodle is there is an additive called...wait for it...SUPER-WATER that helps maintain stream coherence out of a high-pressure waterjet nozzle, allowing even more effective water-only cutting.

Might be interesting to look at how the industrial machines do it: https://www.cticutting.com/tools/

I believe the hobby machines just use rotary cutters but the industrial space is more interesting: - vibratory blade - ultrasonic blade - heated (sealing) blade

BTW laser cutting (non-synthetic) fabric is totally possible and is used in industry, the "hobby" type laser cutters do need some tweaking to get good results: https://www.troteclaser.com/en-gb/knowledge/tips-for-laser-u... Leather does produce a smell that may raise objections ;)

The article does not load for me (database error) but I have cut several types of fabric successfully with a laser. What is the impact to the material? I found it works well for natural fabrics but polyester and nylon can be a bit fiddly to get the settings right. Normally too high power will melt the edge a bit, and you can't cut several layers at once as they will stick together but otherwise it does work ok. Oh, and some wispy fabrics (which are likely plastic based) have a tendency to waft away if the extraction is too strong.

Ditto, laser-cut fabric is amazing. You can get fine detailed slashes and swirls that make for incredible effects, that would be incredibly painstaking to do by hand.

Doesn't it discolor the edges of the fabric?

When do you see the edges of the fabric?

shaped decorations which might be ironed on you would see the edge (you can lightly iron-on with a very flimsy bondaweb then stitch it for security, but you still see the edge)

I suppose if you were cutting white cotton it may? But synthetics generally just.... vanish. It's like cutting with a hot knife but there's no blade.

I can't read the article, because the blog is now down, but it seems somewhat strange to talk about a hypothetical fabric CNC when such machines are readily available and used in industry, including these options and more, as handy modules that you can use for cutting all kinds of fabrics: https://www.zund.com/en/cutting-systems/modules-and-tools

Those machines are probably a bit expensive for private use, but theoretically this seems like it is a solved problem.

The idea was that a home user cannot afford an industrial machine.

You should still learn from the industrial solutions.

Industrial users have real problems that they are highly incentivized to solve. If they solve it a different way from you, you should ask "Why?" and "Can I adapt their solution?".

I can't get to the site either, but there are digital die-cutting machines which use a vacuum bed and very precisely controlled knives to cut all kinds of thin flat materials, including textiles and leather. These machines are not cheap, but they are super useful for softgoods, fashion, packaging, etc. https://www.zund.com/en

How would a vacuum bed work on porous cloth? I guess there would be some kinds of fabric that just wouldn't work.

A sacrificial layer of plastic film above would probably work.

There’s a continuous flow of air through a permeable felt mat. The fabric (or cardboard, or plastic or whatever) doesn’t get stuck like with a suction cup, it’s more like how a vacuum cleaner will pull fabric and it’s difficult to remove. The machine makes a lot of noise when it’s running, due to this suction.

Can't access the page, but one solution I would explore (and suspect has already been explored in depth) would be use of a stiffening treatment (heavy starching) rather than sacrificial sandwich materials. Many fabrics can be starched to be rigid enough to cut with a blade without dragging being a significant issue, and the starch can then be simply washed out.

There was a post in here a while ago on this, I think it was this guys company: https://www.google.com/amp/s/singularityhub.com/2017/02/03/t... . Not sure if it ever went anywhere.

Doesn't look like it, his company website doesn't appear to have been updated since the initial press release:

https://www.sewbo.com/

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